There is a cultural element -- the Japanese perceive the cultural contrast between their world and "ours" more acutely than we do, in both directions (i.e. their positions go from "the West is much better than us" to "the West is so much worse than us" very quickly, it's hard to find level-headed assessments of both positions). Most of the "obviously it can't work" sentiment actually comes from there, in many cases.
And then there is an economic issue: their currency has been so strong for so long, it simply wasn't worth for most medium-to-small companies to invest in tricky oversea expansion for a very long time. Things have changed a bit there, but the cultural perception has not shifted much.
There is also the obvious difficulty of limited chances for local expansion: the country closest to them in cultural terms are Korea, which they historically see as inferior and poorer, and China, which they know they simply cannot match on equal terms.
And then, of course, there is the recent history of train-crash expansion in the '80s. That didn't end well, and some of the lessons they learnt was not to try too hard to expand abroad.